It is certainly possible to reduce the amount of tp that labs provide, but keep in mind that beyond a certain point you will actually be making the game easier.

Basically, it's a lot of tech tree to go over and even with inflated tech costs, the Creative ability still makes it possible to leap forward dramatically.

I've posted a patch file for lower research output in my mod post, in case you want to check it out.

If you take the research value of labs any lower than it is, you may as well build factories and focus research rather than building labs.  The real restriction now is on the number of labs which can be built per planet, which effectively constrains most races to 48 base research on most planets and slows things down quite a bit.

Of course it is possible to do an all-factories approach by using focus and get around that.

Lowering Creative ability is possible, but there are a lot of places besides the race customisation screen where it is available - some of the tech trees have free points available.